Pacemakers or other tissue stimulation devices generally operate to provide an electrical signal which is applied to certain body tissue so as to stimulate or otherwise affect the operation of an organ of the body. The actual stimulation signals are typically generated by a pacemaker or other apparatus which may be surgically implanted within the body, but not in direct contact with the heart or other organ to be regulated, and suitable electrical leads must then be provided to supply the signals from the electronic device to the particular organ of the body. Stimulation of the organ is typically accomplished by implanting or otherwise contacting the organ with an electrode attached to the electrical leads.
Stimulation electrodes are generally available in a variety of shapes and sizes. One such electrode is disclosed in U.S. Pat. No. 3,737,579 (hereby incorporated by reference). The electrode comprises a rigid helix adapted for attachment to body tissue and an insulated conductor attached at its one end to the helix and its other end being adpated for attachment to a power source. The electrode is attached to body tissue by screwing the helix into the body tissue. A device for facilitating the attachment of the electrode is also disclosed. The device comprises a substantially cylindrical-shaped tool having a slot in one end for holding the helical end of the electrode. A groove which extends substantially the entire length of the tool engages and holds the insulated conductor. The helix may be screwed into body tissue by rotating the tool about its longitudinal axis. The helical end of the electrode and the insulated conductor are then separated from the tool.
Separation of the helical end of the electrode from the slot without pulling the helix out of the body tissue or otherwise injuring the body tissue is often difficult. Therefore, it has also been known to provide a longitudinal bore in the attachment device of U.S. Pat. No. 3,737,579. The bore has a rod slidably disposed therein. The rod may be selectively extended to free the electrode from engagement with the slot to avoid damage to tissue in which the electrode is implanted which might otherwise occur if the electrode had to be pulled free from the slot.
A disadvantage of these prior electrodes and electrode implanting devices is that the electrode must be actually implanted in the tissue to determine the effect of stimulation on that particular area of tissue. If the desired effect is not achieved, the electrode must be removed and reimplanted. This procedure often causes undesirable damage to delicate tissue.